Speed up your Windows 2003 Servers (including Citrix)

Here is a very critical Registry entry for Windows 2003 Servers, an entry which affects performance and is so critical that in Vista and Windows 2008, Microsoft actually disables this "feature" by default. I just read this paragraph which is included in the "Performance Tuning Guidelines for Windows Server 2008"

Disabling File Last Access Time Check

Windows Server 2003 and earlier Windows operating systems update the last-accessed time of a file when applications open, read, or write to the file. This increases the number of disk I/Os, which further increases the CPU overhead of virtualization. If applications do not use the last-accessed time on a server, system administrators should consider setting this registry key to disable these updates.

NTFSDisableLastAccessUpdate

HKLM\System\CurrentControlSet\Control\FileSystem\ (REG_DWORD)

By default, both Windows Vista and Windows Server 2008 disable the last-access time updates.